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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. int n, bb[200005], way[10005][10005], res, ans = 1e9, visited[10005][10005], val[200005];
  4. vector<int> adj[200005];
  5.  
  6. void kahn() {
  7.   queue<int> q;
  8.   for (int i = 1; i <= n; i++)
  9.     if (bb[i] == 1)
  10.       q.push(i);
  11.   int u;
  12.   while (!q.empty()) {
  13.     u = q.front();
  14.     q.pop();
  15.     for (int v : adj[u]) {
  16.       if (bb[v] > 1)
  17.         val[v] = max(val[v], val[u] + way[u][v]);
  18.       bb[v]--;
  19.       bb[u]--;
  20.       if (bb[v] == 1)
  21.         q.push(v), visited[u][v] = visited[v][u] = 1;
  22.     }
  23.   }
  24.  
  25.   for (int v : adj[u])
  26.     res = res + val[v] + way[v][u];
  27.   for (int v : adj[u])
  28.     ans = min(ans, max(res -  (way[v][u]+val[v]), val[v]));
  29.   cout << ans;
  30. }
  31.  
  32. int main() {
  33.   ios_base::sync_with_stdio(false);
  34.   cin.tie(nullptr);
  35.   freopen("diameter.inp", "r", stdin);
  36.   freopen("diameter.out", "w", stdout);
  37.   cin >> n;
  38.   for (int i = 1; i < n; i++) {
  39.     int x, y, z;
  40.     cin >> x >> y >> z;
  41.     adj[x].push_back(y);
  42.     adj[y].push_back(x);
  43.     bb[x]++;
  44.     bb[y]++;
  45.     way[x][y] = way[y][x] = z;
  46.   }
  47.   kahn();
  48.  
  49.   return 0;
  50. }
  51.  
Success #stdin #stdout 0.01s 9572KB
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https://ideone.com/uqp7fi
language:
C++14 (gcc 8.3)
created:
7 days ago
visibility:
public

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